I think every LCO runs into this kind of customer from time to time, I know I have. There's really no way of continuing with one of these people. You have to get rid of them.
Sometimes you can save the job by educating them but most of them can't be educated. I've got to the point where I don't spend much time trying to save a job. If the customer isn't happy I thank them for the business they have given me and move on. It's painful if you don't have lots of work but stay in the business long enough and you'll be up to your eyeballs with good customers.